Ladar (Laser Detection and Ranging) is an optical remote sensing technology that measures properties of scattered light to find range and/or other information of a distant target. The sensitivity of focal plane arrays (FPAs) used for ladar and multiple-access lasercom is not sufficient in many instances, so gain is frequently employed to increase the signal level from the FPA. Internal gain, for example as occurs in avalanche photo detectors (APDs), improves sensitivity, but complicates FPA design and signal readout. The use of an external optical image preamplifier to raise the signal above the noise level of the detector array and post-detection electronics can significantly improve system performance; however, image amplifier technology has not generally been adequate for this application. The use of a photopumped semiconductor waveguide amplifier gain medium overcomes many issues with prior art image amplifiers.